Improvement in the manufacture of steel



UNITED "STATES FREDERICK J. SLADE, OF TEENTON, NEW JERSEY.

PATENT OFFIcn IMPROVEMENT IN THE MANUFACTURE OF STEEL.

I Specification forming part of Letters Patent No. 171,183, datedDecember 14, 1875; application filed May 10, 1e75,.

CASE B.

To all whom it may concemi description thereof.

Ordinary crude irons, it is well known, are heterogeneous compounds ofiron and a comparatively small quantity of numerous other substances;but of all the substances usually found in admixture with iron, andwhich it has been heretofore one of the purposes of refining andsteel-making to eliminate, phosphorus has been regarded by manufacturersof cast-steel as the most pernicious for the purposes of their art, notmerely because its effect upon thequality of the steel has beeninjurious, but also, and chiefly, because of the great tenacity withwhich it unites with the iron to resist all processes and agents fortheir separation which have not been found too inconvenient or costlyfor ordinary use in steel-furnaces. Heretofore, all irons containing alarger average proportion been deemed unfit for manufacture intohomogeneous or cast steel. The great bulk of all the iron producedcontains a larger proportion than this of phosphorus; consequently, theiron suitable for steel-makingis comparatively scarce and dear.

Finding that I could notpractically separate the phosphorus from theiron, I have sought to render its presence useful, and discovered thatthis could be doneby expelling, as far as conveniently practicable, allthe other substances, so as to leave the phosphorus in preponderanceover any of them, while it unites with the iron to form an alloy orcombination which is homogeneous, fusible, malleable, and well adaptedto such uses in the arts as require a materialhaving these properties,and which is stronger and more homogeneous than wrought- 11011.

My new method of manufacture therefore utilizes phosphorus in makingcast-steel in such a manner that cheap phosphoric irons may be employedfor conversion into such steel, instead of the more costly irons,containing little phosphorus, heretofore deemed indispensable for thatpurpose.

I have made this steel conveniently and economically by the Martinprocess, in a Siemens reverberatory regenerative gas-furnace, inthe openhearth of which I have charged the quantity and proportions of crudematerials which are usual in the practice of making carbon-steel bymeans of that process and I furnace, such charge consisting of pig-iron,old steel rails, or other steel scrap, and wrought iron, old iron rails,iron-sponge, or scrap iron or iron ore, or any part of these materials,or of cast or wrought iron or steel, in any convenient form andproportions. The phosphorus combined in the materials of the charge maybe in the proportion of from twenty hundredths to fifty hundredths ofone per cent. of the Weight of the iron, according to the wastage in theprocess, and the degrees of fusibility, malleability, and ductilityrequired in the finished product.

Practically, the separation of any excess of phosphorus from the chargein the furnace is too difiicult to be undertaken; therefore, the aim ofthe furnace-man must be in all cases to have a slight deficiency ofphosphorus in the charge, and to compensate that deficiency by means ofcarbon, to be left in or added to the charge, as may be convenient,since any excess of carbon can easily be removed at any stage of theprocess by means of oxidizing or decarbonizing agents. If in any case itshould be expedient for any reason, technical or economical, to usesilicon, chromium, titanium, or other steelifying agentin place ofcarbon, to compensate the deficiency of phosphorus, then the properequivalent quantity of the replacing agent selected lnust be left in oradded to the charge. If, however, through inadvertence or otherwise, thephosphorus should be found to be in excess, and the steel too hard, theniron containing less phosphorus must be added to the molten mass untilthe average proportion of phosphorus shall be sufficiently reduced tomake the steel of the softness or temper required. Small quantities ofthe steel are from to time withdrawn from the bath and tested,

by casting, forging. bending, or otherwise, in order to determine thecondition of the charge, and show .if anything further, and if so, what,is needed to finish it.

After the materials have been melted to-' gether, and the properproportion of each duly established by testing, a quantity ofmanganeseis then to be added, preferably in theformofierro-manganeseorspiegeleisen. From two to ten per cent. of theweight of the charge of the average spiegeleisen of commerce, or itsequivalent of ferro-maganese, will supply the manganese required, theprecise quantity needed in each case being determined by the workman incharge of the furnace, by testing specimens or otherwise, as in theordinary manufacture of carbon-steel by the Martin process.

I have discovered that a maximum ofphosphorus can be combined in thesteel only when it contains a minimum of carbon therefore, in order touse the most phosphoric irons which the process admits, I sought, bymeans of the chemical reactions in the furnace, to

eliminate the carbon to the utmost from the charge, but found apractical necessity for leaving asmall residue, because, when carbon isreduced to a high degree of attenuation, the reaction of oxidizingagents upon the iron grows so intense and Wastes it so rapidly that itbecomes expedient at this point to arrest the elimination of the carbon.The steel thus made is soft, malleable, and ductile, but not veryfusible when the proportion of phosphorus combined in it is small; butas the proportion of phosphorus is increased the steelis rendered morefusible, and less malleable and ductile.

deem it unnecessary herein to describe more particularly the manner ofworking the Martin process, or of constructing and managing the Siemensfurnace, or in what manner this steel might be made, with the aid of theexplanations herein given, by other known processes of working in otherfurnaces or aption of the phosphorus already in the steel to the desiredextent, substantially as described and set forth.

= FRED. J. SLADE.

Witnesses: I g

R. W. RAYMOND,

P. H. WATSON.

